No one with undetectable viral load transmitted HIV in Partner Study
The second larger study to see whether people with HIV become non-infectious if they are on antiretroviral therapy (ART) found no cases where someone with a viral load below 200 copies / ml of HIV transmitted by anal or vaginal sex.
A statistical analysis showed that the most likely chance of transmission by anal sex from someone on successful HIV treatment was 1% per year and 4% for anal sex with ejaculation where the HIV-negative partner was passive.
But the true probability is probably much closer to zero than that.
When asked what the study told us about the chance of someone with an undetectable viral load, the lecturer Alison Rodger said: "Our best estimate is that it is zero."
The studyHPTN 052, Undetectable Viral Load and HIV Transmission
The previous study HPTN 052, established in 2011 that the effectiveness of antiretroviral therapy to reduce HIV transmission from HIV-positive partner to the HIV-negative was at least 96% in heterosexual couples, but had very few gay couples in the study to establish whether the same was true to them (or instead of anal sex).
O PARTNER study was created to remedy this gap in knowledge. So far he recruited 1110 couples where partners have different HIV status - and about 40% of them are gay couples.
To participate in this study, couples have to be having sex without a condom at least part of the time.
The HIV-negative partner may not be using pre- or post-exposure prophylaxis (PEP or PrEP) and the HIV-positive partner must be on ART, with the most recent viral load below 200 copies / ml. This study is different from HPTN052 that mediates the efficacy of HIV-positive partners initiating therapy (versus partners who had not started).
In total, 767 couples participated in this interim analysis of two years and there was a total of 894 accompaniments contraceptives. Among heterosexual couples, HIV serostatus was divided into equal parts - in half the couples man had HIV and the other half, the woman.
Gay couples were and sex without condom with undetectable viral load
Some couples were excluded from analysis. In most cases, this was because they did not appear in the follow-up visits, but in 16% of cases it was because the HIV-positive partner has developed a viral load above 200 copies / ml, and 3% of cases because HIV partner -negative took PEP or PrEP.
There were significant differences between gay couples and heterosexual couples. At baseline, gay couples were doing unprotected sex for a period shorter on average: 1,5 years versus 2,5 for heterosexual men and 3,5 for women.
HIV-negative heterosexual partners with undetectable viral load reported having had vaginal intercourse without a condom, 72% with ejaculation
During the monitoring period, all heterosexual HIV-negative partners reported having vaginal sex without a condom, 72% with ejaculation; 70% of HIV-negative gay partners reported receptive anal sex with ejaculation 40%, while 30% reported only be the active partner. A significant proportion of heterosexual couples reported having had anal sex (will be reported later).
Unprotected sex outside the relationship was much more common among gay men - a third of HIV-negative partners reported that, versus 3-4% of heterosexuals. There is no doubt that because of this, sexually transmitted infections (STIs) were much more common in gay couples, with 16% of gay men developing an STI (especially gonorrhea or syphilis) during follow-up versus 5% of heterosexuals.
The results of unprotected intercourse with undetectable viral load
The main news is that the PARTNER until now there has been transmission in couples with a partner with an undetectable viral load, as was estimated to 16.400 occasions of sex in gay men and heterosexual in 28.000.
Although some of the HIV-negative partners became HIV-positive (the exact number will be revealed at a later analysis), genetic HIV tests revealed that in all cases the virus came from someone other than the primary partner.
Alison Rodger told the conference that the HIV-positive partners were not in treatment in this group, 50-100 (average: 86) transmissions would have been expected in gay couples, and 15 transmission in heterosexual couples.
No transmission is not the same as odds of zero transmission. The researchers calculated the 95% confidence intervals for the observed results. What this means is that they calculated the odds of zero transmissions being the fact 'true' and what was the maximum risk of transmission, given the observed results.
They established that there was a chance that 95% (in a couple where sexual activity is average for the study group) the largest possible risk of transmission of a partner was 0,45% per year and anal sex 1% per year .
In a press conference, Dr. Jens Lundgren, principal investigator of the PARTNER study, pointed out that this meant that there was a maximum chance of 5% over a period of 10 years, one in 10 partners in a gay couple who had sex unprotected anal could acquire HIV; also, well, it was more likely that your chance of acquiring HIV from their partners was very close to zero, and in fact could be zero.
As the group, the study group becomes smaller, as most become the confidence intervals and the certainty of a result becomes 'vague'. This means that the maximum probability of someone transmission chance in suppressive therapy of HIV in their highest degree was 2% per year for anal sex with ejaculation, 2,5% for receptive anal sex, and 4% for receptive anal sex with ejaculation. The latter figure implies more than one in three chance of infection if the sexual behavior remain unchanged for more than ten years, but again, this is one of the 'worst' scenarios and the likelihood is probably lower.
No transmission occurred despite relatively high levels of STIs, especially in gay couples. When the 'Switzerland Declaration' (Swiss Statement, in English) was released in 2008, she stated that people with an undetectable viral load did not transmit HIV, but made an exception in people with STI: the study PARTNER may be telling us that STIs (in positive or negative partners) do not increase the likelihood of HIV transmission if the positive partner is on ART and undetectable (although, of course, can still be transmitted to them).
The PARTNER is recruiting gay men and couples, as noted above, its full results will not leave before 2017. Until then we need to be careful about what he proved, and as Jen Lundgren said, will never be displayed with mathematical certainty that the risk of someone transmission in successful HIV therapy is absolutely zero. Furthermore, these results exclude situations where the failed ART HIV-positive partner, although there were few of these cases.
Translation:Rodrigo Sgobbi Pellegrini
After the publication of this text there is more to be seen this linkand I advise reading
The Rodger et al. HIV transmission risk through condomless fri IF HIV + partner on Supressive ART: PARTNER study. Conference on Retroviruses 21st and Opportunistic Infections, Boston, abstract 153LB, 2014.